This invention relates to multiple cone-type strutless synchronizers for manual transmissions and more particularly to an improved triple cone blocker ring strutless synchronizer incorporating servo action.
Strutless synchronizers, such as disclosed in the U.S. Pat. No. 3,700,083 issued Oct. 29, 1972 to N. Ashikawa et al, are well known in the synchromesh transmission art. The '083 patent employs an annular spring interposed between a sleeve, slidably mounted on a hub on a main shaft, and a blocker ring provided on the conical slidable surface of a speed ratio gear. The annular spring is slidably mounted in a snug manner on the outer surface of three uniformly spaced axially extending lugs integrally formed as the blocking ring. The annular spring interposed between the sleeve and the blocker ring lugs is so arranged that upon movement of the sleeve, the annular spring is first pushed axially by certain of the sleeve internal uniformly spaced splines. This in turn causes the annular spring to axially push the blocker ring. The blocker ring is then seated on the gear cone which, having a relative rotational speed, generates a cone torque to index or clock the blocker ring to the desired blocking position. Once synchronization is complete, the annular spring is then compressed and deflected radially inward by the sleeve as the sleeve passes over the spring. As a result, the sleeve internal splines mesh with a driven gear journaled on the main shaft and thus rotation of the main shaft is transmitted to the driven gear.
The U.S. Pat. No. 4,623,054 issued Nov. 18, 1986 to Barksdale discloses a dual cone pin type synchronizing clutch having multiple conical friction elements for synchronizing the speeds of a shaft and a gear wheel before clutch engagement. The '054 patent includes a cone element member rotatably supported on a gear wheel and free to rotate relative to a conical friction surface on the gear wheel. A hub is splined to the shaft and has external teeth engaged by internal teeth of the synchronizer clutch sleeve. The clutch sleeve defines blocking surfaces that contact mating blocking surfaces on a cone arm assembly. As the clutch sleeve is moved axially by the vehicle operator during gear change, the cone arm assembly is moved axially bringing the conical surface into contact with the mating friction surfaces on an intermediate cone member fixed to the gear wheel. This frictional engagement operates to synchronize the speeds of the gear wheel and the clutch hub before the sleeve is moved axially further into mechanical engagement with the clutching teeth on the gear wheel.